1. Field of the Invention
The present invention relates to cultivating devices which can be used to grow and harvest shellfish such as bivalve mollusks, and especially oysters.
2. The Prior Art
Cultivating devices for providing protective environments in which shellfish such as bivalve mollusks (e.g., oysters) can grow to maturity are well known. Some of the known cultivating devices include separate trays or drawers which are positionable on top of one another in support housings which can be lowered into bodies of water. Such cultivating devices are disclosed, for example, in U.S. Pat. Nos. 3,702,599, 3,741,159 and 4,061,110. However, these prior art cultivating devices are very laborsome and time consuming to service because it is not possible to transfer the shellfish from one tray thereof to another tray without removing each of the trays from the support housing. In addition, these prior art cultivating devices are not capable of cultivating commercial quantities of shellfish (e.g. oysters) because they are not constructed to take into consideration the expansion (scale up) of the growing area which is needed for the shellfish to grow to a fully mature size. Instead, they enable shellfish to grow to only limited sizes (for oysters, about 3/4 inch in length), after which the shellfish must be transported to open water bottoms for final growth. During this final growth procedure fishermen (oystermen) must manually shift the shellfish (oysters) around with dredges and rakes so as to give them sufficient room to grow to maturity. This is of course very labor intensive and tends to defeat one of the main objectives of artificial shellfish propagation, which is of course to make the whole process more efficient and productive.